code: def test_init(self):
      bbox_head = SABLHead(
          cls_in_channels=1,
          cls_out_channels=1,
          reg_in_channels=1,
          reg_offset_out_channels=1,
          reg_cls_out_channels=1,
          num_classes=4,
      )
      self.assertTrue(bbox_head.fc_cls)
      self.assertTrue(hasattr(bbox_head, "reg_cls_fcs"))
      self.assertTrue(hasattr(bbox_head, "reg_offset_fcs"))
      self.assertFalse(hasattr(bbox_head, "fc_reg"))
  
file_path: mmdetection/tests/test_models/test_roi_heads/test_bbox_heads/test_sabl_bbox_head.py
imports: from unittest import TestCase
  import torch
  from mmengine.config import ConfigDict
  from mmengine.structures import InstanceData
  from mmdet.models.roi_heads.bbox_heads import SABLHead
  from mmdet.models.task_modules.samplers import SamplingResult
label_desc: Use image node_id 1 for calling the TestSABLBboxHead obj's underlying member method code with example usage: obj.test_init() without return types